An example of a disk rotor of this type is disclosed in the specification of Japanese Utility Model Laid-Open (KOKAI) No. 54-52576. As shown in FIGS. 1 and 2, the disk rotor has a disk portion 1 and a columnar hat portion 2 formed integral with the disk portion 1. An annular groove 1a is formed along the entire circumferential surface of the disk portion 1, and a metal wire 3 is wound on the disk portion 1 so as to engage the annular groove 1a. The metal wire 3 is fixed to the circumferential surface of the disk portion 1 by welding 4 at one or more points.
However, a problem encountered in the prior-art disk rotor is that unwelded portions of the metal wire 3 lift up from the circumferential surface of the disk portion 1 for such reasons as a difference in coefficient of thermal expansion between the disk portion 1 and the metal wire 3, as a result of which vibration of the disk rotor produced at braking cannot be completely absorbed.